Scalar Fluxes Near a Tall Building in an Aligned Array of Rectangular Buildings

Fuka, Vladimír; Xie, Zheng-Tong; Castro, Ian P.; Hayden, Paul; Carpentieri, Matteo; Robins, Alan

doi:10.1007/s10546-017-0308-4

Cited by 52 publications

(39 citation statements)

References 33 publications

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“…Xu et al 2017), heat (e.g. Yang et al 2010;Yang and Li 2015), and pollutant dispersion and street-canyon ventilation (Brixey et al 2009;Heist et al 2009;Fuka et al 2018). All of these aspects challenge the general applicability of current urban-modelling concepts in high-rise cities at the local scale and mesoscale (Barlow et al 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Daniels et al 2013;Elshaer et al 2016;Le and Caracoglia 2016), the effect of a tall building's wake on low-lying surroundings and on the overall structure of the downwind urban boundary layer is still not well explored. Heist et al (2009) and Fuka et al (2018) showed that tall buildings in idealized street systems considerably affect the street-canyon flow. The downward flow on the windward face of the tall building intensifies the vortex in the upwind street canyon and outflow from this street is enhanced (horizontal flow divergence).…”

Section: Introductionmentioning

confidence: 99%

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Wake Characteristics of Tall Buildings in a Realistic Urban Canopy

Hertwig

Gough

Grimmond

et al. 2019

Boundary-Layer Meteorol

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The presence of tall buildings in cities affects momentum and scalar exchange within and above the urban canopy. As wake effects can be important over large distances, they are crucial for urban-flow modelling on and across different spatial scales. We explore the aerodynamic effects of tall buildings on the microscale to local scales with a focus on the interaction between the wake structure, canopy and roughness sublayer flow of the surroundings in a realistic urban setting in central London. Flow experiments in a boundary-layer wind tunnel use a 1:200 scale model with two tall buildings (81 m and 134.3 m) for two wind directions. Large changes in mean flow, turbulence statistics and instantaneous flow structure of the wake are evident when tall buildings are part of the complex urban canopy rather than isolated. In the near-wake, the presence of lower buildings displaces the core of the recirculation zone upwards, thereby reducing the vertical depth over which flow reversal occurs. This amplifies vertical shear at the rooftop and enhances turbulent momentum exchange. In the near part of the main wake, lateral velocity fluctuations and hence turbulence kinetic energy are reduced compared to the isolated building case as eddies generated in the urban canopy and roughness sublayer distribute energy down to smaller scales that dissipate more rapidly. Evaluation of a wake model for flow past isolated buildings suggests model refinements are needed to account for such flow-structure changes in tall-building canopies. Keywords Tall-building environments • Urban canopy • Urban flow • Wake model • Wind tunnel Nomenclature H Building (roof) height H NoTall Mean building height (No Tall) H ave Mean building height Electronic supplementary material The online version of this article (

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Wake Characteristics of Tall Buildings in a Realistic Urban Canopy

Hertwig

Gough

Grimmond

et al. 2019

Boundary-Layer Meteorol

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“…Large-Eddy Simulations have demonstrated the capability to model turbulence, dispersion and heat transfer in urban environments (Baker et al, 2004;Fuka et al, 2017;Hanna et al, 2002;Kanda et al, 2004;Xie & Castro, 2006).…”

Section: Introductionmentioning

confidence: 99%

Turbulence and dispersion below and above the interface of the internal and the external boundary layers

Sessa

Xie

Herring

2018

Journal of Wind Engineering and Industrial Aerodynamics

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This study has looked at the development of the internal boundary layer (IBL) over a block array close to a sharp change in surface roughness and its effect on dispersion from a ground level source for ratios of the downstream distance to the roughness length of less than 300. This was done by comparing a Large-Eddy Simulation (LES) with inflow boundary conditions against a LES with inlet-outlet periodic boundary conditions and data from a wind tunnel experiment. In addition to established methods, an alternative approach based on the vertical Reynolds stress was used to evaluate the depth of the IBL as it developed over the array which enabled the location of the interface to be more clearly defined. It was confirmed that the IBL growth rate close to the change in surface roughness could be described by a power law profile, similar to the power law formula used in previous studies for a ratio of the downstream distance to the roughness length greater than 1000. An analysis of mean concentration and turbulent scalar fluxes suggested that the presence of the IBL constrained the vertical development of the plume from a ground level source and so led to trapping of material in the canopy layer.

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“…This paper aims to investigate this subject by introducing a more complex geometry (rectangular buildings rotated by 45 • instead of cubes) and multiple SBL and CBL strengths. The same geometry was already studied by Castro et al (2017) and Fuka et al (2018) for neutral stratification. Great emphasis has also been dedicated to the characteristics of the approaching flow, as described in details by Marucci et al (2018).…”

Section: Introductionmentioning

confidence: 86%

Stable and convective boundary-layer flows in an urban array

Marucci

Carpentieri

2020

Journal of Wind Engineering and Industrial Aerodynamics

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In this paper non-neutral approaching flows were employed in a meteorological wind tunnel on a regular urban-like array of rectangular buildings. As far as stable stratification is concerned, results on the flow above and inside the canopy show a clear reduction of the Reynolds stresses and an increment of the Monin-Obukhov length up to 80%. The roughness length and displacement height were also affected, with a reduction up to 35% for the former and an increment up to 12% for the latter. A clear reduction of the turbulence within the canopy was observed. In the convective stratification cases, the friction velocity appears increased by both the effect of roughness and unstable stratification. The increased roughness causes a reduction in the surface stratification, reflected in an increase of the Monin-Obukhov length, which is double over the array compared to the approaching flow. The effect on the aerodynamic roughness length and displacement height are specular to the SBL case, an increase up to 50% of the former and a reduction of the same amount for the latter.

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Scalar Fluxes Near a Tall Building in an Aligned Array of Rectangular Buildings

Cited by 52 publications

References 33 publications

Wake Characteristics of Tall Buildings in a Realistic Urban Canopy

Wake Characteristics of Tall Buildings in a Realistic Urban Canopy

Turbulence and dispersion below and above the interface of the internal and the external boundary layers

Stable and convective boundary-layer flows in an urban array

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